How to investigate further a seemingly 'ghost' commit (after a merge)?

Hello, 

I am trying to understand how a fix from a bug-correction branch vanished and 
the bug found its way back into the main branch after two merges. 

I am using git version 2.19.2. 

Checkouting tag 18.40.1 and checking its graph: 

$ git checkout 18.40.1 

$ git log --oneline --graph 
* ee4721a1 (HEAD, tag: 18.40.1) Merge branch 'suppressionNumAdhCTP' into 'homol2' 
|\ 
| * 52aeaf64 Retire le numéro de contrat et le numéro d'adhérent qui étaient affichés en haut de la page et empiétaient sur le préimprimé. 
|/ 
* 9f68ec4b (tag: 18.40.0) Merge branch 'cherry-pick-7c956b5f' into 'homol2' 

For the record, here is the git log excerpt on the file in question: 

$ git log app/CTPCB-AC001/CTPCB-AC001.tex 
commit 52aeaf64c808c1e3ee8c5cbf5f0221d4e8a7699d 
Author: Guillaume Ballin < guillaume.ballin@mnt.fr > 
Date: Tue Nov 13 11:52:03 2018 +0100 

Retire le numéro de contrat et le numéro d'adhérent qui étaient affichés en haut de la page et empiétaient sur le préimprimé. 

commit 9336db5c25bb0f3af19183fe1db2fb05ce28b9f3 
Author: arnavander < arnavander@mnt.fr > 
Date: Mon Nov 5 14:46:27 2018 +0000 

Correction retour anomalie de Carte TP 

Signed-off-by: arnavander < arnavander@mnt.fr > 


(cherry picked from commit 7c956b5f29bf23c624684c9300a13abecfb451c5) 

Checkouting commit 25ca67a9 and checking its graph: 

$ git checkout 25ca67a9 

$ git log --oneline --graph 
* 25ca67a9 (HEAD) Merge branch 'homol2' into 'homol' 
|\ 
| * ee4721a1 (tag: 18.40.1) Merge branch 'suppressionNumAdhCTP' into 'homol2' 
| |\ 
| | * 52aeaf64 Retire le numéro de contrat et le numéro d'adhérent qui étaient affichés en haut de la page et empiétaient sur le préimprimé. 
| |/ 
| * 9f68ec4b (tag: 18.40.0) Merge branch 'cherry-pick-7c956b5f' into 'homol2' 

Checking the log of that file again: 

$ git log app/CTPCB-AC001/CTPCB-AC001.tex 
commit 7c956b5f29bf23c624684c9300a13abecfb451c5 
Author: arnavander < arnavander@mnt.fr > 
Date: Mon Nov 5 15:46:27 2018 +0100 

Correction retour anomalie de Carte TP 

Signed-off-by: arnavander < arnavander@mnt.fr > 

Commit 52aeaf64c808c1e3ee8c5cbf5f0221d4e8a7699d does not show up any more in 
the pointed to by commit 25ca67a9! 

The fix only deleted a block of lines: 

How a commit can disapear like that from the log of a file and of course not 
patching the file while staying visible in the git log of the branch? 
It's just like if grandchildren forgetted grandparent commit while staying connected 
to parents... 

--
Fan2linux - G. Ballin